The invention relates to a mechanically stable screen cloth construction made of metal.
The use of metal elements as structural reinforcers for catalysts for the purification of automobile exhaust gases is known. Thus in a series of publications (U.S. Pat. No. 3,920,583, German OS No. 23 02 746, German OS No. 24 50 644) a catalyst matrix of non-scaling steel has been described, which consists of an extended metallic carrier, in the case of which steel sheets of a certain thickness are developed as plain planar and, corrugated sheets, and are arranged alternatingly in layers.
In the German AS No. 21 64 123 a catalyst material in the form of one or more layers of a coated screen with variable dimensions and mesh width and in the form of coated mats, made of crinkled wire, had been described. The use of wire mesh compared to carriers fabricated of metal ribbons has the advantage of a lower weight and a higher geometric surface.
Furthermore, carrier matrixes for catalysts have already been described which consist of layers arranged one on top of the other, of high temperature resistant and non-scaling steel, whereby the layers consist of planar screen cloth into which spacers of a larger cross section than the screening have been woven on or in at parallel distances in the direction of the desired flow channels, or whereby layers of planar screen cloth or corrugated sheet metal alternate with layers of planar or corrugated screen cloth.
Another advantage of such gas permeable matrixes as compared to systems made of metal ribbons, is a cross stream effect promoting the catalysis and an improved supporting capacity relative to catalysis promoting metal oxides present in an immersion dispersion. Known systems made of wire mesh, however, should be improved in their stability as in regard to mechanical deformation.
In the case of modern internal combustion engines, the requirements for mechanical stability are indeed extraordinarily high. As a result of the ignition sequence of a piston engine, catalysts as well as lead or carbon particle filters or condensate filters are admitted with the exhaust gases, which are characterized by strong pulsations. The latter, in the case of known matrix systems, may soon lead to the mechanical destruction of the catalyst support or of the exhaust gas particle filter.